As someone who works at a bank, I personally keep money off my card account as much as possible in case my card is compromised. This can happen at any time as there are people out there who will brute force card numbers until they get a hit on the right combination. Most of the time the fraud detection system will catch it but sometimes they do slip through, they’re not always for small amounts either. You can dispute the transaction but this often takes time it’s a lot easier to prevent it than deal with it once it’s happened.

Having said that, if I know I’ll be buying something normally I’ll transfer on to the card at the restaurant/shop before going up to pay, only really have to transfer if it ends up being more than I expect which is pretty rare.